One that president Obama warned today would be, quote, a long-term project. And just tonight, the Pentagon announcing four new air strikes. Earlier today we saw these images of the first U.S. Air strikes on terror targets in northern Iraq. The gunner's eye view of missiles taking out militants and weapons below. Meanwhile parachuting from U.S. Cargo planes, huge bundles of food and water. For humanitarian aid for refugees stranded on a mountain top. Today the refugees are on the move again. Looking to escape the violence. We have team coverage. We begin with ABC white house correspondent, Jonathan Karl, traveling with the president. Jon? Reporter: Good evening. The president arrived in Martha's vineyard is afternoon. He already played a round of golf but also spoken to the leaders of Germany, France, and Britain. The attention focused thousands of miles away on the military operation in Iraq. As 500-pound bombs dropped from fighter jets and missiles fired from predator drones, pummeled targets in northern Iraq. President Obama bluntly acknowledged there is no clear end date on this military operation. I don't think we'll solve this problem in weeks. I think this is going to take some time. The Iraqi security forces. In order to mount an offensive, and operate effectively with the support of populations in the Sunni areas, will have to revamp. Get resupplied, have a clear strategy. Reporter: Although the president reaffirmed his promise not to send ground troops -- Because we should have learned a lesson from our long and immensely costly incursion in Iraq. Reporter: He described a broader mission for U.S. Air strikes than he did just two days ago, when he said the sole objectives, were to protect Americans, especially 150 Americans serving in the northern Iraqi city of erbil and prevent a genocide of a minority group surrounded on a mountain top by a terror group known as isil. Today, he said something more. We have to make sure isil is not engaging in actions that could cripple a country permanently. Reporter: Of immediate concern, the terrorists have taken control of Iraq's largest dam which not only sblies electricity to some 1.5 million Iraqis, but if destroyed, could send a tsunami of water all of the way from mosul, from the north to Baghdad, even threatening the U.S. Embassy. The president said he's keeping congressional leaders informed about the situation in Iraq but doesn't need to go back to congress yet to ask for additional money for air strikes. Jonathan Karl, thank you. I want bring in ABC's correspondent, Martha rad its who was just in Iraq a nothing ago. What is the concern here? Reporter: The crisis can be mitigated in the next few weeks but not going away. What if they move towards Baghdad. You have to ramp up the air strikes again. The goal of protecting Americans is not going to end as long as Americans are in Iraq, and they have to be there to make sure terrorists don't establish a safe haven and the humanitarian crisis is ongoing until you get those people off that mountain and into a safer place. That will be complicated and dangerous and take time, Byron. Martha, what is the bottom line here? Reporter: The bottom line, we're back in Iraq in a significant way, and to sustain what president Obama said he wants to sustain, and it will keep us involved and on alert there for the foreseeable future. Martha Raddatz in Washington. Thank you, Martha. Martha will have the latest on the growing crisis in Iraq

This transcript has been automatically generated and may not be 100% accurate.